Of course there is the plumb bob and screw in lens cap method: Pass plumb bob string through barrel from muzzle through chamber, and then through the mouth and flash hole of an empty case of the same caliber as the rifle, securing it by tying it around an old style RCBS decapping pin. Chamber case with bolt unclosed. Remove the front lens cap, and drill a small hole through its exact center (see earlier post for directions for finding center), and pass another plumb bob string through the hole and secure as with the barrel bob. Put the cap back on the scope. Hang the rifle from a garage rafter tie so that the bore is plumb, as verified by symmetrical depth mic readings from the outside of the muzzle to the outside of the string. Adjust bobs so that their points are just above the floor. Lay a finely divided steel rule under the points and using a magnifying glass and LED flashlight note and record the distance between the points. Safety tips: String should be removed from barrel before attempting to fire rifle, and front scope cap should be removed unless rifle is fitted with Iron Sighter rings, in which case it can be left in place. In any case it is suggested that the string and bob be removed , and the hole in the cap filled with well chewed bubble gum, that may later be Cerakoted to match the cap. If all has gone well and you have obtained a reading between 1/2 and 6" destroy any evidence of the process used and sell the rifle, as you are way too gullible to be shooting anything.
